Radical-component oxide etch

ABSTRACT

A method of etching exposed silicon oxide on patterned heterogeneous structures is described and includes a remote plasma etch formed from a fluorine-containing precursor. Plasma effluents from the remote plasma are flowed into a substrate processing region where the plasma effluents combine with a nitrogen-and-hydrogen-containing precursor. Reactants thereby produced etch the patterned heterogeneous structures with high silicon oxide selectivity while the substrate is at high temperature compared to typical Siconi™ processes. The etch proceeds without producing residue on the substrate surface. The methods may be used to remove silicon oxide while removing little or no silicon, polysilicon, silicon nitride or titanium nitride.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of and claims benefit to U.S. patentapplication Ser. No. 13/834,611, filed Mar. 15, 2013, which claimsbenefit to U.S. Prov. Pat. App. No. 61/702,493 filed Sep. 18, 2012, andtitled “RADICAL-COMPONENT OXIDE ETCH,” both of which are herebyincorporated herein in their entirety by reference for all purposes.

BACKGROUND OF THE INVENTION

Integrated circuits are made possible by processes which produceintricately patterned material layers on substrate surfaces. Producingpatterned material on a substrate requires controlled methods forremoval of exposed material. Chemical etching is used for a variety ofpurposes including transferring a pattern in photoresist into underlyinglayers, thinning layers or thinning lateral dimensions of featuresalready present on the surface. Often it is desirable to have an etchprocess which etches one material faster than another helping e.g. apattern transfer process proceed. Such an etch process is said to beselective to the first material. As a result of the diversity ofmaterials, circuits and processes, etch processes have been developedwith a selectivity towards a variety of materials.

A wet HF etch preferentially removes silicon oxide over otherdielectrics and semiconductors. However, wet processes are unable topenetrate some constrained trenches and sometimes deform the remainingmaterial. Dry etches produced in local plasmas (plasmas within thesubstrate processing region) can penetrate more constrained trenches andexhibit less deformation of delicate remaining structures. However,local plasmas can damage the substrate through the production ofelectric arcs as they discharge.

A Siconi™ etch is a remote plasma assisted dry etch process whichinvolves the simultaneous exposure of a substrate to H₂, NF₃ and NH₃plasma by-products. Remote plasma excitation of the hydrogen andfluorine species allows plasma-damage-free substrate processing. TheSiconi™ etch is largely conformal and selective towards silicon oxidelayers but does not readily etch silicon regardless of whether thesilicon is amorphous, crystalline or polycrystalline. Silicon nitride istypically etched at a rate between silicon and silicon oxide, but theselectivity of silicon oxide over silicon nitride is typically not aspronounced as the selectivity of silicon oxide over silicon. Theselectivity provides advantages for applications such as shallow trenchisolation (STI) and inter-layer dielectric (ILD) recess formation. TheSiconi™ process produces solid by-products which grow on the surface ofthe substrate as substrate material is removed. The solid by-productsare subsequently removed via sublimation when the temperature of thesubstrate is raised. As a consequence of the production of solidby-products, Siconi™ etch process can deform delicate remainingstructures as well.

Methods are needed to selectively remove silicon oxide while not formingsolid by-products on the surface since their formation may disturbdelicate structures on a patterned substrate.

BRIEF SUMMARY OF THE INVENTION

A method of etching exposed silicon oxide on patterned heterogeneousstructures is described and includes a remote plasma etch formed from afluorine-containing precursor. Plasma effluents from the remote plasmaare flowed into a substrate processing region where the plasma effluentscombine with a nitrogen-and-hydrogen-containing precursor. Reactantsthereby produced etch the patterned heterogeneous structures with highsilicon oxide selectivity while the substrate is at high temperaturecompared to typical Siconi™ processes. The etch proceeds withoutproducing residue on the substrate surface. The methods may be used toremove silicon oxide while removing little or no silicon, polysilicon,silicon nitride or titanium nitride.

Embodiments of the invention include methods of etching patternedsubstrates in a substrate processing region of a substrate processingchamber. The patterned substrates have an exposed silicon oxide region.The methods include flowing a fluorine-containing precursor into aremote plasma region fluidly coupled to the substrate processing regionwhile forming a remote plasma in the remote plasma region to produceplasma effluents. The methods further include flowing anitrogen-and-hydrogen-containing precursor into the substrate processingregion without first passing the nitrogen-and-hydrogen-containingprecursor through the remote plasma region. The methods further includeetching the exposed silicon oxide region with the combination of theplasma effluents and the nitrogen-and-hydrogen-containing precursor inthe substrate processing region.

Additional embodiments and features are set forth in part in thedescription that follows, and in part will become apparent to thoseskilled in the art upon examination of the specification or may belearned by the practice of the disclosed embodiments. The features andadvantages of the disclosed embodiments may be realized and attained bymeans of the instrumentalities, combinations, and methods described inthe specification.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the disclosedembodiments may be realized by reference to the remaining portions ofthe specification and the drawings.

FIG. 1 is a flow chart of a silicon oxide selective etch processaccording to disclosed embodiments.

FIG. 2A shows a substrate processing chamber according to embodiments ofthe invention.

FIG. 2B shows a showerhead of a substrate processing chamber accordingto embodiments of the invention.

FIG. 3 shows a substrate processing system according to embodiments ofthe invention.

In the appended figures, similar components and/or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If only the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

DETAILED DESCRIPTION OF THE INVENTION

A method of etching exposed silicon oxide on patterned heterogeneousstructures is described and includes a remote plasma etch formed from afluorine-containing precursor. Plasma effluents from the remote plasmaare flowed into a substrate processing region where the plasma effluentscombine with a nitrogen-and-hydrogen-containing precursor. Reactantsthereby produced etch the patterned heterogeneous structures with highsilicon oxide selectivity while the substrate is at high temperaturecompared to typical Siconi™ processes. The etch proceeds withoutproducing residue on the substrate surface. The methods may be used toremove silicon oxide while removing little or no silicon, polysilicon,silicon nitride or titanium nitride.

Selective remote gas phase etch processes have used a hydrogen source ofammonia (NH₃) and a fluorine source of nitrogen trifluoride (NF₃) whichtogether flow through a remote plasma system (RPS) and into a reactionregion. The flow rates of ammonia and nitrogen trifluoride are typicallychosen such that the atomic flow rate of hydrogen is roughly twice thatof fluorine in order to efficiently utilize the constituents of the twoprocess gases. The presence of hydrogen and fluorine allows theformation of solid byproducts of (NH₄)₂SiF₆ at relatively low substratetemperatures. The solid byproducts are removed by raising thetemperature of the substrate above the sublimation temperature. Remotegas phase etch processes remove oxide films much more rapidly than, e.g.silicon. However, the selectivity of traditional selective remote gasphase etch processes compared to silicon nitride may be poor. Theinventors have discovered that the selectivity of silicon oxide oversilicon nitride can be enhanced by exciting a fluorine-containingprecursor in a remote plasma and combining the plasma effluents withammonia which has not passed through a remote plasma system.

In order to better understand and appreciate the invention, reference isnow made to FIG. 1 which is a flow chart of a silicon oxide selectiveetch process according to disclosed embodiments. Prior to the firstoperation, the substrate is patterned leaving exposed regions of siliconoxide and exposed regions of silicon nitride. The patterned substrate isthen delivered into a substrate processing region (operation 110). Aflow of nitrogen trifluoride is initiated into a plasma region separatefrom the processing region (operation 120). Other sources of fluorinemay be used to augment or replace the nitrogen trifluoride. In general,a fluorine-containing precursor is flowed into the plasma region and thefluorine-containing precursor comprises at least one precursor selectedfrom the group consisting of atomic fluorine, diatomic fluorine,nitrogen trifluoride, carbon tetrafluoride, hydrogen fluoride and xenondifluoride. The separate plasma region may be referred to as a remoteplasma region herein and may be within a distinct module from theprocessing chamber or a compartment within the processing chamber. Theplasma effluents formed in the remote plasma region are then flowed intothe substrate processing region (operation 125). At this point, the gasphase etch would have little selectivity towards silicon oxide and wouldhave limited utility. However, ammonia is simultaneously flowed into thesubstrate processing region (operation 130) to react with the plasmaeffluents. The ammonia is not passed through the remote plasma regionand therefore is only excited by interaction with the plasma effluents.

The patterned substrate is selectively etched (operation 135) such thatthe silicon oxide is removed at a significantly higher rate than thesilicon nitride. The reactive chemical species are removed from thesubstrate processing region and then the substrate is removed from theprocessing region (operation 145). Using the gas phase dry etchprocesses described herein, the inventors have established that etchselectivities of over 100:1 and up to 150:1 (SiO etch rate:SiN etchrate) are possible. Achievable selectivities using the methods describedherein are at least four times greater than prior art methods. Thesilicon oxide etch rate exceeds the silicon nitride etch rate by amultiplicative factor of about 40 or more, about 50 or more, about 75 ormore, or about 100 or more, in embodiments of the invention.

The gas phase dry etches described herein have also been discovered toincrease etch selectivity of silicon oxide relative to silicon(including polysilicon). Using the gas phase dry etch processesdescribed herein, the inventors have established that etch selectivitiesof over 100:1 and up to 500:1 (SiO etch rate:Si etch rate) are possible.Achievable selectivities using the methods described herein are at leastfive times greater than prior art methods. The silicon oxide etch rateexceeds the silicon etch rate by a multiplicative factor of about 100 ormore, about 150 or more, about 200 or more, or about 300 or more, inembodiments of the invention.

Gas phase etches involving only fluorine (either remote or local) do notpossess the selectivity needed to remove the silicon oxide while leavingother portions of the patterned substrate (e.g. made of silicon orsilicon nitride) nearly undisturbed. The gas phase etches describedherein have an added benefit, in that they do not produce solid residue.Elimination of solid residue avoids disturbing delicate features whichmay be supported by sacrificial silicon oxide. Elimination of solidresidue also simplifies the process flows and decreases processing costsby removing the sublimation step. The fluorine-containing precursor isdevoid of hydrogen in embodiments of the invention. The plasma effluentsmay also be devoid of hydrogen when no hydrogen precursors are includedin the remote plasma region. This ensures minimal production of solidby-products on the patterned substrate.

Without wishing to bind the coverage of the claims to theoreticalmechanisms which may or may not be entirely correct, some discussion ofpossible mechanisms may prove beneficial. Radical-fluorine precursorsare produced by delivering a fluorine-containing precursor into theremote plasma region. Applicants suppose that a concentration offluorine ions and atoms is produced and delivered into the substrateprocessing region. Ammonia (NH₃) may react with the fluorine to produceless reactive species such as HF₂ ⁻ which still readily remove siliconoxide but do not readily remove silicon and silicon nitride from thepatterned substrate surface. The selectivity combined with the lack ofsolid byproducts, make these etch processes well suited for removingmolds and other silicon oxide support structures from delicatenon-silicon oxide materials while inducing little deformation in theremaining delicate structures.

Generally speaking, a nitrogen-and-hydrogen-containing precursor may beused in place of the ammonia. The nitrogen-and-hydrogen-containingprecursor may consist only of nitrogen and hydrogen, e.g. ammonia (NH₃)used in the above example. The nitrogen-and-hydrogen-containingprecursor may be hydrazine (N₂H₄) in disclosed embodiments.

The pressure in the substrate processing region may be above or about0.1 Torr and less than or about 50 Torr, in disclosed embodiments,during the etching operation. The pressure within the substrateprocessing region may also be below or about 40 Torr and above or about5 Torr or 10 Torr in disclosed embodiments. Any of the upper limits canbe combined with any of these lower limits to form additionalembodiments of the invention. The temperature of the patterned substratemay be about 10° C. or more and about 250° C. or less, in disclosedembodiments, during the etching operation. The temperature of thepatterned substrate may be about 100° C. or more and about 140° C. orless during the etching operation in embodiments of the invention.

In addition to the fluorine-containing precursor, an oxygen-containingprecursor may be delivered to the remote plasma region during theetching operation. The inventors have found that adding theoxygen-containing precursor broadens the process window whilemaintaining the selectivity benefits outlined above. The pressure is theprocess parameter which can vary more widely through the addition of theoxygen-containing precursor. A broader pressure range is possible (whilemaintaining uniform selective etch process) when an oxygen-containingprecursor is added to the remote plasma region during the etchingoperation. The oxygen-containing precursor may be molecular oxygen (O₂),nitrous oxide (N₂O) or nitrogen dioxide (NO₂), for example, though otheroxygen-containing precursors may be used.

Additional silicon oxide selective etch process parameters are disclosedin the course of describing an exemplary processing chamber and system.

Exemplary Processing System

Processing chambers that may implement embodiments of the presentinvention may be included within processing platforms such as theCENTURA® and PRODUCER® systems, available from Applied Materials, Inc.of Santa Clara, Calif. Examples of substrate processing chambers thatcan be used with exemplary methods of the invention may include thoseshown and described in co-assigned U.S. Provisional Patent App. No.60/803,499 to Lubomirsky et al, filed May 30, 2006, and titled “PROCESSCHAMBER FOR DIELECTRIC GAPFILL,” the entire contents of which is hereinincorporated by reference for all purposes. Additional exemplary systemsmay include those shown and described in U.S. Pat. Nos. 6,387,207 and6,830,624, which are also incorporated herein by reference for allpurposes.

FIG. 2A is a substrate processing chamber 1001 according to disclosedembodiments. A remote plasma system (RPS 1010) may process thefluorine-containing precursor which then travels through a gas inletassembly 1011. Two distinct gas supply channels are visible within thegas inlet assembly 1011. A first channel 1012 carries a gas that passesthrough the remote plasma system RPS 1010, while a second channel 1013bypasses the RPS 1010. Either channel may be used for thefluorine-containing precursor, in embodiments. On the other hand, thefirst channel 1002 may be used for the process gas and the secondchannel 1013 may be used for a treatment gas. The lid 1021 (e.g. aconducting top portion) and a perforated partition (showerhead 1053) areshown with an insulating ring 1024 in between, which allows an ACpotential to be applied to the lid 1021 relative to showerhead 1053. TheAC potential strikes a plasma in chamber plasma region 1020. The processgas may travel through first channel 1012 into chamber plasma region1020 and may be excited by a plasma in chamber plasma region 1020 aloneor in combination with RPS 1010. If the process gas (thefluorine-containing precursor) flows through second channel 1013, thenonly the chamber plasma region 1020 is used for excitation. Thecombination of chamber plasma region 1020 and/or RPS 1010 may bereferred to as a remote plasma system herein. The perforated partition(also referred to as a showerhead) 1053 separates chamber plasma region1020 from a substrate processing region 1070 beneath showerhead 1053.Showerhead 1053 allows a plasma present in chamber plasma region 1020 toavoid directly exciting gases in substrate processing region 1070, whilestill allowing excited species to travel from chamber plasma region 1020into substrate processing region 1070.

Showerhead 1053 is positioned between chamber plasma region 1020 andsubstrate processing region 1070 and allows plasma effluents (excitedderivatives of precursors or other gases) created within RPS 1010 and/orchamber plasma region 1020 to pass through a plurality of through-holes1056 that traverse the thickness of the plate. The showerhead 1053 alsohas one or more hollow volumes 1051 which can be filled with a precursorin the form of a vapor or gas (such as a silicon-containing precursor)and pass through small holes 1055 into substrate processing region 1070but not directly into chamber plasma region 1020. Showerhead 1053 isthicker than the length of the smallest diameter 1050 of thethrough-holes 1056 in this disclosed embodiment. In order to maintain asignificant concentration of excited species penetrating from chamberplasma region 1020 to substrate processing region 1070, the length 1026of the smallest diameter 1050 of the through-holes may be restricted byforming larger diameter portions of through-holes 1056 part way throughthe showerhead 1053. The length of the smallest diameter 1050 of thethrough-holes 1056 may be the same order of magnitude as the smallestdiameter of the through-holes 1056 or less in disclosed embodiments.

In the embodiment shown, showerhead 1053 may distribute (viathrough-holes 1056) process gases which contain oxygen, hydrogen and/ornitrogen and/or plasma effluents of such process gases upon excitationby a plasma in chamber plasma region 1020. In embodiments, the processgas introduced into the RPS 1010 and/or chamber plasma region 1020through first channel 1012 may contain fluorine (e.g. CF₄, NF₃ or XeF₂).The process gas may also include a carrier gas such as helium, argon,nitrogen (N₂), etc. Plasma effluents may include ionized or neutralderivatives of the process gas and may also be referred to herein as aradical-fluorine precursor referring to the atomic constituent of theprocess gas introduced.

In embodiments, the number of through-holes 1056 may be between about 60and about 2000. Through-holes 1056 may have a variety of shapes but aremost easily made round. The smallest diameter 1050 of through-holes 1056may be between about 0.5 mm and about 20 mm or between about 1 mm andabout 6 mm in disclosed embodiments. There is also latitude in choosingthe cross-sectional shape of through-holes, which may be made conical,cylindrical or a combination of the two shapes. The number of smallholes 1055 used to introduce a gas into substrate processing region 1070may be between about 100 and about 5000 or between about 500 and about2000 in different embodiments. The diameter of the small holes 1055 maybe between about 0.1 mm and about 2 mm.

FIG. 2B is a bottom view of a showerhead 1053 for use with a processingchamber according to disclosed embodiments. Showerhead 1053 correspondswith the showerhead shown in FIG. 2A. Through-holes 1056 are depictedwith a larger inner-diameter (ID) on the bottom of showerhead 1053 and asmaller ID at the top. Small holes 1055 are distributed substantiallyevenly over the surface of the showerhead, even amongst thethrough-holes 1056 which helps to provide more even mixing than otherembodiments described herein.

An exemplary patterned substrate may be supported by a pedestal (notshown) within substrate processing region 1070 when fluorine-containingplasma effluents arriving through through-holes 1056 in showerhead 1053combine with ammonia arriving through the small holes 1055 originatingfrom hollow volumes 1051. Though substrate processing region 1070 may beequipped to support a plasma for other processes such as curing, noplasma is present during the etching of patterned substrate, inembodiments of the invention.

A plasma may be ignited either in chamber plasma region 1020 aboveshowerhead 1053 or substrate processing region 1070 below showerhead1053. A plasma is present in chamber plasma region 1020 to produce theradical-fluorine precursors from an inflow of the fluorine-containingprecursor. An AC voltage typically in the radio frequency (RF) range isapplied between the conductive top portion 1021 of the processingchamber and showerhead 1053 to ignite a plasma in chamber plasma region1020 during deposition. An RF power supply generates a high RF frequencyof 13.56 MHz but may also generate other frequencies alone or incombination with the 13.56 MHz frequency.

The top plasma may be left at low or no power when the bottom plasma inthe substrate processing region 1070 is turned on to either cure a filmor clean the interior surfaces bordering substrate processing region1070. A plasma in substrate processing region 1070 is ignited byapplying an AC voltage between showerhead 1053 and the pedestal orbottom of the chamber. A cleaning gas may be introduced into substrateprocessing region 1070 while the plasma is present.

The pedestal may have a heat exchange channel through which a heatexchange fluid flows to control the temperature of the substrate. Thisconfiguration allows the substrate temperature to be cooled or heated tomaintain relatively low temperatures (from room temperature throughabout 120° C.). The heat exchange fluid may comprise ethylene glycol andwater. The wafer support platter of the pedestal (preferably aluminum,ceramic, or a combination thereof) may also be resistively heated inorder to achieve relatively high temperatures (from about 120° C.through about 1100° C.) using an embedded single-loop embedded heaterelement configured to make two full turns in the form of parallelconcentric circles. An outer portion of the heater element may runadjacent to a perimeter of the support platter, while an inner portionruns on the path of a concentric circle having a smaller radius. Thewiring to the heater element passes through the stem of the pedestal.

The substrate processing system is controlled by a system controller. Inan exemplary embodiment, the system controller includes a hard diskdrive, a floppy disk drive and a processor. The processor contains asingle-board computer (SBC), analog and digital input/output boards,interface boards and stepper motor controller boards. Various parts ofCVD system conform to the Versa Modular European (VME) standard whichdefines board, card cage, and connector dimensions and types. The VMEstandard also defines the bus structure as having a 16-bit data bus anda 24-bit address bus.

The system controller controls all of the activities of the etchingchamber. The system controller executes system control software, whichis a computer program stored in a computer-readable medium. Preferably,the medium is a hard disk drive, but the medium may also be other kindsof memory. The computer program includes sets of instructions thatdictate the timing, mixture of gases, chamber pressure, chambertemperature, RF power levels, susceptor position, and other parametersof a particular process. Other computer programs stored on other memorydevices including, for example, a floppy disk or other anotherappropriate drive, may also be used to instruct the system controller.

A process for depositing a film stack on a substrate or a process forcleaning a chamber can be implemented using a computer program productthat is executed by the system controller. The computer program code canbe written in any conventional computer readable programming language:for example, 68000 assembly language, C, C++, Pascal, Fortran or others.Suitable program code is entered into a single file, or multiple files,using a conventional text editor, and stored or embodied in a computerusable medium, such as a memory system of the computer. If the enteredcode text is in a high level language, the code is compiled, and theresultant compiler code is then linked with an object code ofprecompiled Microsoft Windows® library routines. To execute the linked,compiled object code the system user invokes the object code, causingthe computer system to load the code in memory. The CPU then reads andexecutes the code to perform the tasks identified in the program.

The interface between a user and the controller is via a flat-paneltouch-sensitive monitor. In the preferred embodiment two monitors areused, one mounted in the clean room wall for the operators and the otherbehind the wall for the service technicians. The two monitors maysimultaneously display the same information, in which case only oneaccepts input at a time. To select a particular screen or function, theoperator touches a designated area of the touch-sensitive monitor. Thetouched area changes its highlighted color, or a new menu or screen isdisplayed, confirming communication between the operator and thetouch-sensitive monitor. Other devices, such as a keyboard, mouse, orother pointing or communication device, may be used instead of or inaddition to the touch-sensitive monitor to allow the user to communicatewith the system controller.

The chamber plasma region or a region in an RPS may be referred to as aremote plasma region. In embodiments, the radical precursor (e.g. aradical-fluorine precursor) is created in the remote plasma region andtravels into the substrate processing region to combine with theammonia. In embodiments, the ammonia is excited only by theradical-fluorine precursor. Plasma power may essentially be applied onlyto the remote plasma region, in embodiments, to ensure that theradical-fluorine precursor provides the dominant excitation to theammonia.

In embodiments employing a chamber plasma region, the excited plasmaeffluents are generated in a section of the substrate processing regionpartitioned from a deposition region. The deposition region, also knownherein as the substrate processing region, is where the plasma effluentsmix and react with the ammonia to etch the patterned substrate (e.g., asemiconductor wafer). The excited plasma effluents may also beaccompanied by inert gases (in the exemplary case, argon). The ammoniadoes not pass through a plasma before entering the substrate plasmaregion, in embodiments. The substrate processing region may be describedherein as “plasma-free” during the etch of the patterned substrate.“Plasma-free” does not necessarily mean the region is devoid of plasma.Ionized species and free electrons created within the plasma region dotravel through pores (apertures) in the partition (showerhead) but theammonia is not substantially excited by the plasma power applied to theplasma region. The borders of the plasma in the chamber plasma regionare hard to define and may encroach upon the substrate processing regionthrough the apertures in the showerhead. In the case of aninductively-coupled plasma, a small amount of ionization may be effectedwithin the substrate processing region directly. Furthermore, a lowintensity plasma may be created in the substrate processing regionwithout eliminating desirable features of the forming film. All causesfor a plasma having much lower intensity ion density than the chamberplasma region (or a remote plasma region, for that matter) during thecreation of the excited plasma effluents do not deviate from the scopeof “plasma-free” as used herein.

Nitrogen trifluoride (or another fluorine-containing precursor) may beflowed into chamber plasma region 1020 at rates between about 25 sccmand about 200 sccm, between about 50 sccm and about 150 sccm or betweenabout 75 sccm and about 125 sccm in disclosed embodiments. Ammonia maybe flowed into substrate processing region 1070 at rates between about25 sccm and about 200 sccm, between about 50 sccm and about 150 sccm orbetween about 75 sccm and about 125 sccm in disclosed embodiments. Theoptional oxygen-containing precursor may be flowed into chamber plasmaregion 1020 at rates between about 15 sccm and about 200 sccm, betweenabout 25 sccm and about 150 sccm or between about 50 sccm and about 125sccm in embodiments of the invention.

Combined flow rates of ammonia and fluorine-containing precursor intothe chamber may account for 0.05% to about 20% by volume of the overallgas mixture; the remainder being carrier gases. The fluorine-containingprecursor is flowed into the remote plasma region but the plasmaeffluents has the same volumetric flow ratio, in embodiments. In thecase of the fluorine-containing precursor, a purge or carrier gas may befirst initiated into the remote plasma region before those of thefluorine-containing gas to stabilize the pressure within the remoteplasma region.

Plasma power can be a variety of frequencies or a combination ofmultiple frequencies. In the exemplary processing system the plasma isprovided by RF power delivered to lid 1021 relative to showerhead 1053.The RF power may be between about 10 watts and about 2000 watts, betweenabout 100 watts and about 2000 watts, between about 200 watts and about1500 watts or between about 500 watts and about 1000 watts in differentembodiments. The RF frequency applied in the exemplary processing systemmay be low RF frequencies less than about 200 kHz, high RF frequenciesbetween about 10 MHz and about 15 MHz or microwave frequencies greaterthan or about 1 GHz in different embodiments. The plasma power may becapacitively-coupled (CCP) or inductively-coupled (ICP) into the remoteplasma region.

Substrate processing region 1070 can be maintained at a variety ofpressures during the flow of ammonia, any carrier gases and plasmaeffluents into substrate processing region 1070. The pressure may bemaintained between about 500 mTorr and about 30 Torr, between about 1Torr and about 20 Torr or between about 5 Torr and about 15 Torr indisclosed embodiments.

In one or more embodiments, the substrate processing chamber 1001 can beintegrated into a variety of multi-processing platforms, including theProducer™ GT, Centura™ AP and Endura™ platforms available from AppliedMaterials, Inc. located in Santa Clara, Calif. Such a processingplatform is capable of performing several processing operations withoutbreaking vacuum. Processing chambers that may implement embodiments ofthe present invention may include dielectric etch chambers or a varietyof chemical vapor deposition chambers, among other types of chambers.

Embodiments of the deposition systems may be incorporated into largerfabrication systems for producing integrated circuit chips. FIG. 3 showsone such system 1101 of deposition, baking and curing chambers accordingto disclosed embodiments. In the figure, a pair of FOUPs (front openingunified pods) 1102 supply substrate substrates (e.g., 300 mm diameterwafers) that are received by robotic arms 1104 and placed into a lowpressure holding area 1106 before being placed into one of the substrateprocessing chambers 1108 a-f. A second robotic arm 1110 may be used totransport the substrate wafers from the holding area 1106 to thesubstrate processing chambers 1108 a-f and back. Each substrateprocessing chamber 1108 a-f, can be outfitted to perform a number ofsubstrate processing operations including the dry etch processesdescribed herein in addition to cyclical layer deposition (CLD), atomiclayer deposition (ALD), chemical vapor deposition (CVD), physical vapordeposition (PVD), etch, pre-clean, degas, orientation and othersubstrate processes.

The substrate processing chambers 1108 a-f may include one or moresystem components for depositing, annealing, curing and/or etching aflowable dielectric film on the substrate wafer. In one configuration,two pairs of the processing chamber (e.g., 1108 c-d and 1108 e-f) may beused to deposit dielectric material on the substrate, and the third pairof processing chambers (e.g., 1108 a-b) may be used to etch thedeposited dielectric. In another configuration, all three pairs ofchambers (e.g., 1108 a-f) may be configured to etch a dielectric film onthe substrate. Any one or more of the processes described may be carriedout on chamber(s) separated from the fabrication system shown indifferent embodiments.

System controller 1157 is used to control motors, valves, flowcontrollers, power supplies and other functions required to carry outprocess recipes described herein. A gas handling system 1155 may also becontrolled by system controller 1157 to introduce gases to one or all ofthe substrate processing chambers 1108 a-f. System controller 1157 mayrely on feedback from optical sensors to determine and adjust theposition of movable mechanical assemblies in gas handling system 1155and/or in substrate processing chambers 1108 a-f. Mechanical assembliesmay include the robot, throttle valves and susceptors which are moved bymotors under the control of system controller 1157.

In an exemplary embodiment, system controller 1157 includes a hard diskdrive (memory), USB ports, a floppy disk drive and a processor. Systemcontroller 1157 includes analog and digital input/output boards,interface boards and stepper motor controller boards. Various parts ofmulti-chamber processing system 1101 which contains processing chamber1001 are controlled by system controller 1157. The system controllerexecutes system control software in the form of a computer programstored on computer-readable medium such as a hard disk, a floppy disk ora flash memory thumb drive. Other types of memory can also be used. Thecomputer program includes sets of instructions that dictate the timing,mixture of gases, chamber pressure, chamber temperature, RF powerlevels, susceptor position, and other parameters of a particularprocess.

A process for etching, depositing or otherwise processing a film on asubstrate or a process for cleaning chamber can be implemented using acomputer program product that is executed by the controller. Thecomputer program code can be written in any conventional computerreadable programming language: for example, 68000 assembly language, C,C++, Pascal, Fortran or others. Suitable program code is entered into asingle file, or multiple files, using a conventional text editor, andstored or embodied in a computer usable medium, such as a memory systemof the computer. If the entered code text is in a high level language,the code is compiled, and the resultant compiler code is then linkedwith an object code of precompiled Microsoft Windows® library routines.To execute the linked, compiled object code the system user invokes theobject code, causing the computer system to load the code in memory. TheCPU then reads and executes the code to perform the tasks identified inthe program.

The interface between a user and the controller may be via atouch-sensitive monitor and may also include a mouse and keyboard. Inone embodiment two monitors are used, one mounted in the clean room wallfor the operators and the other behind the wall for the servicetechnicians. The two monitors may simultaneously display the sameinformation, in which case only one is configured to accept input at atime. To select a particular screen or function, the operator touches adesignated area on the display screen with a finger or the mouse. Thetouched area changes its highlighted color, or a new menu or screen isdisplayed, confirming the operator's selection.

As used herein “substrate” may be a support substrate with or withoutlayers formed thereon. The patterned substrate may be an insulator or asemiconductor of a variety of doping concentrations and profiles andmay, for example, be a semiconductor substrate of the type used in themanufacture of integrated circuits. Exposed “silicon oxide” of thepatterned substrate is predominantly SiO₂ but may include concentrationsof other elemental constituents such as nitrogen, hydrogen, carbon andthe like. In some embodiments, silicon oxide films etched using themethods disclosed herein consist essentially of silicon and oxygen. Theterm “precursor” is used to refer to any process gas which takes part ina reaction to either remove material from or deposit material onto asurface. “Plasma effluents” describe gas exiting from the chamber plasmaregion and entering the substrate processing region. Plasma effluentsare in an “excited state” wherein at least some of the gas molecules arein vibrationally-excited, dissociated and/or ionized states. A “radicalprecursor” is used to describe plasma effluents (a gas in an excitedstate which is exiting a plasma) which participate in a reaction toeither remove material from or deposit material on a surface. A“radical-fluorine precursor” is a radical precursor which containsfluorine but may contain other elemental constituents. A “radical-oxygenprecursor” is a radical precursor which contains oxygen but may containother elemental constituents. The phrase “inert gas” refers to any gaswhich does not form chemical bonds when etching or being incorporatedinto a film. Exemplary inert gases include noble gases but may includeother gases so long as no chemical bonds are formed when (typically)trace amounts are trapped in a film.

The terms “gap” and “trench” are used throughout with no implicationthat the etched geometry has a large horizontal aspect ratio. Viewedfrom above the surface, trenches may appear circular, oval, polygonal,rectangular, or a variety of other shapes. A trench may be in the shapeof a moat around an island of material (e.g. a substantially cylindricalTiN pillar). The term “via” is used to refer to a low aspect ratiotrench (as viewed from above) which may or may not be filled with metalto form a vertical electrical connection. As used herein, a conformaletch process refers to a generally uniform removal of material on asurface in the same shape as the surface, i.e., the surface of theetched layer and the pre-etch surface are generally parallel. A personhaving ordinary skill in the art will recognize that the etchedinterface likely cannot be 100% conformal and thus the term “generally”allows for acceptable tolerances.

Having disclosed several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of thedisclosed embodiments. Additionally, a number of well known processesand elements have not been described in order to avoid unnecessarilyobscuring the present invention. Accordingly, the above descriptionshould not be taken as limiting the scope of the invention.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimits of that range is also specifically disclosed. Each smaller rangebetween any stated value or intervening value in a stated range and anyother stated or intervening value in that stated range is encompassed.The upper and lower limits of these smaller ranges may independently beincluded or excluded in the range, and each range where either, neitheror both limits are included in the smaller ranges is also encompassedwithin the invention, subject to any specifically excluded limit in thestated range. Where the stated range includes one or both of the limits,ranges excluding either or both of those included limits are alsoincluded.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural referents unless the context clearly dictatesotherwise. Thus, for example, reference to “a process” includes aplurality of such processes and reference to “the dielectric material”includes reference to one or more dielectric materials and equivalentsthereof known to those skilled in the art, and so forth.

Also, the words “comprise,” “comprising,” “include,” “including,” and“includes” when used in this specification and in the following claimsare intended to specify the presence of stated features, integers,components, or steps, but they do not preclude the presence or additionof one or more other features, integers, components, steps, acts, orgroups.

What is claimed is:
 1. A method of etching a patterned substrate in asubstrate processing region of a substrate processing chamber, whereinthe patterned substrate has an exposed silicon oxide region, the methodcomprising: flowing a fluorine-containing precursor into a remote plasmaregion fluidly coupled to the substrate processing region while forminga remote plasma in the remote plasma region to produce plasma effluents;flowing a nitrogen-and-hydrogen-containing precursor into the substrateprocessing region without first passing thenitrogen-and-hydrogen-containing precursor through the remote plasmaregion; flowing the plasma effluents through a showerhead separating theremote plasma region from the substrate processing region; and etchingthe exposed silicon oxide region with the combination of the plasmaeffluents and the nitrogen-and-hydrogen-containing precursor in thesubstrate processing region.
 2. The method of claim 1 further comprisingflowing an oxygen-containing precursor into the remote plasma regionduring the formation of the remote plasma.
 3. The method of claim 1further comprising flowing one of molecular oxygen, nitrogen dioxide ornitrous oxide into the remote plasma region during the formation of theremote plasma.
 4. The method of claim 1 wherein thenitrogen-and-hydrogen-containing precursor consists of nitrogen andhydrogen.
 5. The method of claim 1 wherein thenitrogen-and-hydrogen-containing precursor comprises ammonia.
 6. Themethod of claim 1 wherein the patterned substrate further comprises anexposed polysilicon region and the selectivity of the etching operation(exposed silicon oxide region: exposed polysilicon region) is greaterthan or about 50:1.
 7. The method of claim 1 wherein the patternedsubstrate further comprises an exposed polysilicon region and theselectivity of the etching operation (exposed silicon oxide region:exposed polysilicon region) is greater than or about 100:1.
 8. Themethod of claim 1 wherein the patterned substrate further comprises anexposed silicon nitride region and the selectivity of the etchingoperation (exposed silicon oxide region: exposed silicon nitride region)is greater than or about 30:1.
 9. The method of claim 1 wherein thepatterned substrate further comprises an exposed silicon nitride regionand the selectivity of the etching operation (exposed silicon oxideregion: exposed silicon nitride region) is greater than or about 70:1.10. The method of claim 1 wherein the substrate processing region isplasma-free.
 11. The method of claim 1 wherein thenitrogen-and-hydrogen-containing precursor is not excited by any remoteplasma formed outside the substrate processing region.
 12. The method ofclaim 1 wherein the fluorine-containing precursor comprises a precursorselected from the group consisting of atomic fluorine, diatomicfluorine, nitrogen trifluoride, carbon tetrafluoride, hydrogen fluorideand xenon difluoride.
 13. The method of claim 1 wherein thefluorine-containing precursor and the plasma effluents are essentiallydevoid of hydrogen.
 14. The method of claim 1 wherein thefluorine-containing precursor flowed through through-holes in adual-zone showerhead and the ammonia passes through separate zones inthe dual-zone showerhead, wherein the separate zones open into thesubstrate processing region but not into the remote plasma region. 15.The method of claim 1 wherein a temperature of the patterned substrateis greater than or about 10° C. and less than or about 250° C. duringthe etching operation.
 16. The method of claim 1 wherein a temperatureof the patterned substrate is greater than or about 100° C. and lessthan or about 140° C. during the etching operation.
 17. The method ofclaim 1 wherein a pressure within the substrate processing region isbelow or about 50 Torr and above or about 0.1 Torr during the etchingoperation.
 18. The method of claim 1 wherein forming a plasma in theremote plasma region to produce plasma effluents comprises applying RFpower between about 10 Watts and about 2000 Watts to the plasma region.19. The method of claim 1 wherein a plasma in the remote plasma regionis a capacitively-coupled plasma.